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y band sky brightness varies over a night, from High, Stubbs et al PASP paper on y band variability:
Some observations:
- Sky brightness contribution from OH typically varies by a factor of two over the course of a single night, darkest at midnight. This corresponds to 0.25 mag change in m5.
- For the OH contribution from slab of emission in the upper atmosphere, we'd expect sky darkest at zenith, getting brighter proportional to airmass
- Clouds produce scattered moonlight, so in grey time the night sky brightness doesn't have lunar angle dependence that's built into current version of opsim
- We definitely want a real-time adaptive scheduler, that optimizes based on both cloud transparency and sky brightness.
Merit Function Ingredients.
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